Search king Google is known for constantly tweaking its product line for marketers. In the past year, Google has been transitioning to the product listing ad (PLA) model for paid search. The format allows marketers to present rich information to online searchers including price, image and merchant name, instead of just text, and the software behind the system doesn’t require the marketer to add more keywords or text. A new Marin study finds that consumers are clicking on the PLAs at a high rate and this trend may encourage marketers to invest more in this form of paid search advertising.